Problem: A String is called Palindrome if it reads the same backwards as well as forwards.  For example, the String aba can be read the same backwards as well as forwards. 
Now, a Permutation of a String S is some String K where S and K contain the same set of characters, however, these characters need not necessarily have the same positions.   For Example, consider the String abc. Here, the Strings :
acb  
bca  
bac  
cab  
cba

are all permutations of it. 

Now, given a String S consisting of lowercase English alphabets, you need to find out whether any permutation of this given String is a Palindrome. If yes, print "YES" (Without quotes) else, print "NO" without quotes.  

Input Format:
The first and only line of input contains the String S. 

Output Format:
Print the required answer on a single line

Constraints:
 1 ≤ |S| ≤ 1000 
 S[i] ∈ [a,z] 

SAMPLE INPUT
abab

SAMPLE OUTPUT
YES

Explanation

Here, the permutation  abba is a palindrome.

Solution (in PYTHON):

Solution:
from sys import stdin
a = stdin.readline().strip()
di = {}
od = 0
for i in a:
	di[i] = di.get(i,0) + 1
for i in di:
	if di[i]%2:
		od+=1
ans = 'NO'
if od < 2:
	ans = 'YES'
print ans